<?php
class SysCrypt {
    private $crypt_key;
    public function __construct($crypt_key = '' ) {
        $this -> crypt_key = $crypt_key;
    }
    public function setkey($key){
        $this->crypt_key = $key;
    }
    public function php_encrypt($txt) {
        srand((double)microtime() * 1000000);
        $encrypt_key = md5(rand(0,32000));
        $ctr = 0;
        $tmp = '';
        for($i = 0;$i<strlen($txt);$i++) {
            $ctr = $ctr == strlen($encrypt_key) ? 0 : $ctr;
            $tmp .= $encrypt_key[$ctr].($txt[$i]^$encrypt_key[$ctr++]);
        }
        return base64_encode(self::__key($tmp,$this -> crypt_key));
    }
    public function php_decrypt($txt) {
        $txt = self::__key(base64_decode($txt),$this -> crypt_key);
        $tmp = '';
        for($i = 0;$i < strlen($txt); $i++) {
            $md5 = $txt[$i];
            $tmp .= $txt[++$i] ^ $md5;
        }
        return $tmp;
    }
    private function __key($txt,$encrypt_key) {
        $encrypt_key = md5($encrypt_key);
        $ctr = 0;
        $tmp = '';
        for($i = 0; $i < strlen($txt); $i++) {
            $ctr = $ctr == strlen($encrypt_key) ? 0 : $ctr;
            $tmp .= $txt[$i] ^ $encrypt_key[$ctr++];
        }
        return $tmp;
    }
    public function __destruct() {
        $this -> crypt_key = null;
    }
}
?>
